The present invention relates to a double-ended medical needle and a holder therefor, and a blood collection and/or injection device which employs such a double-ended medical needle and a holder therefor, and more particularly to an improvement in a hub/holder connector structure which comprises a double-ended medical needle including a cannula which has opposite pointed ends, with a hub fitted over the cannula, a tubular holder for holding the hub of the medical needle, and an evacuated blood collection tube or syringe insertable into the holder through an opening thereof for communication with the cannula of the medical needle.
Heretofore, there have widely been employed devices for collecting blood samples from or injecting medicine into human bodies through double-ended medical needles.
FIG. 1 of the accompanying drawings illustrates one such conventional evacuated blood collection device, and FIG. 2 shows a conventional injection/blood collection device.
The evacuated blood collection device shown in FIG. 1 comprises a medical needle 2, a holder 4, and an evacuated blood collection tube 6. The injection/blood collection device shown in FIG. 2 comprises a medical needle 2, a holder 4, and a syringe 8. The medical needles 2 and the holders 4 shown in FIGS. 1 and 2 are of identical structures, respectively.
The medical needle 2 comprises a cannula 10 having opposite pointed ends 10a, 10b, a hub 12 fitted over an intermediate portion of the cannula 10 and supporting the same, and a rubber sheath 14 fitted over an end portion of the cannula 10 and joined to one end of the hub 12. Since the rubber sheath 14 is fitted over the end portion of the cannula 10, the rubber sheath 14 prevents blood from flowing into the holder 4 when blood samples are collected successively into a plurality of evacuated blood collection tube 6 while the cannula 10 is being inserted in a blood vessel.
The holder 4 holds the medical needle 2 through the hub 12, and is in the form of a hollow cylinder made of a transparent plastic material or the like.
The evacuated blood collection tube 6 comprises a bottomed glass tube 16 and a rubber plug 18 closing the open end of the glass tube 16, the rubber plug 18 being penetratable by the cannula 10. Normally, the interior space of the glass tube 16 is evacuated so that it can draw and collect a necessary amount of blood.
The syringe 8 comprises a syringe cylinder 20 and a pusher 24 with a packing 22 mounted on one end thereof. The pusher 24 can be inserted into the syringe cylinder 20 through an open end thereof, with the packing 22 held in close contact with the inner surface of the syringe cylinder 20.
To use the evacuated blood collection device shown in FIG. 1, the medical needle 2 is threaded into the holder 4, and then the evacuated blood collection tube 6 is pushed into the holder 4 through the open end thereof to force one pointed end 10b of the cannula 10 into the rubber plug 18, but not fully through the rubber plug 18. Thereafter, the holder 4 is held by the operator and the other pointed end 10a of the cannula 10 is caused to penetrate a blood vessel in an arm or the like of a blood donor. While the arm and the holder 4 are being fixed relatively to each other, the evacuated blood collection tube 6 is further pushed in to force the pointed end 10b of the cannula 10 all the way through the rubber plug 18, thus allowing blood to flow through the cannula 10 into the evacuated blood collection tube 6.
To use the injection/blood collection device shown in FIG. 2, the medical needle 2 is threaded into the holder 4, and then the syringe 8 is pushed into the holder 4 through the open end thereof until the pointed end 10b of the cannula 10 is inserted into the other open end of the syringe cylinder 20 and positioned therein. The holder 4 is held by the operator and the other pointed end 10a of the cannula 10 is inserted into a blood vessel in an arm or the like of a blood donor or a patient. While the arm and the holder 4 are being fixed relatively to each other, the pusher 24 is pulled out to draw blood through the cannula 10 into the syringe cylinder 10, or the pusher 24 is pushed in to inject medicine from the syringe 8 into the blood vessel. Thereafter, the syringe 8 is pulled out of the holder 4 while the holder 4 is firmly held with respect to the arm, and then a new syringe is connected again to the holder 4.
With the conventional structures described above, however, the palm of a hand or a finger of the operator may be penetrated by the medical needle 2 when it is replaced.
More specifically, in order to remove the medical needle 2 from the holder 4, the medical needle 2 is covered with a protector (not shown), and then the medical needle 2 is unscrewed from the holder 4. When the medical needle 2 is covered with a protector, the palm of a hand or a finger of the operator may be pierced by the medical needle 2. To avoid such an accident, therefore, it is desirable for the operator to be able to throw away only the medical needle 2 without covering the needle 2 with a protector and also without touching the needle 2.
If the needle 2 is not sufficiently threaded into the holder 4, the needle 2 may get loose when the blood collection tube 6 or syringe 8 is connected to the holder 4. It is also troublesome to thread the medical needle 2 into the holder 4. For these reasons, there has been a demand for a structure which facilitates a simple connection between the medical needle 2 and the holder 4.
To meet such a demand, there has been proposed a structure by which a hub and a holder can be connected to each other by an inserting and fitting process as disclosed in Japanese Laid-Open Patent Publication No. 62(1987)-148646. According to the disclosed arrangement, a medical needle can be replaced in one operation so that a blood collection/injection device employing such a medical needle can simply be mounted in place on a blood donor or a patient.